Air-oil unit



April 29, 1958 Filed Sept. 20. 1955 FIG.2

R. W. ERIIKSON AIR-OIL UNIT 2 Sheets-Sheet 1 ,INVENTOR ROBERT W. ERIKSON lav/M, 7,4

ATTORN FYS April 29, 1958 R. w. ERIKSON AIR-OIL UNIT 2 Sheets-Sheet 2 Filed Sept. 20, 1955 INVENTOR ROBERT WfERIKSON fl 5 p ATTORNEYS United AIR-OIL UNIT Robert W. Erikson, Rockford, Ill., assignor to Sundstrand This invention relates to an air-oil system for supplying air and oil to a device such as an oil-burner nozzle, and has for a general object the provision of a new and improved system of the type described.

it is a more specific object of the invention to provide, in an air-oil unit having a pump and an air blower for supplying oil and air to a burner nozzle, a new and improved control system for the .oil and air deliveries thereof.

Another object is to provide a new and improved system of the character described including an oil passage for connecting the oil pump to the nozzle, an air conduit for connecting the air blower to the nozzle, a valve for blocking the oil passage, an air motor communicating with the air conduit for operating the valve to open the passage when the air pressure reaches a first predetermined value, p

and an air bleed operable by the valve for bleeding the conduit when the air pressure reaches a second, higher predetermined value.

A further object is to provide a new and improved system of the type described in the preceding paragraph wherein the air bleed establishes communication between the air conduit and the intake side of the air blower so that air bled from the conduit is returned to the blower.

Another object is to provide a new and improved system of the type described wherein the valve for controlling the oil passage includes a valve bore having a slidable valve member with separated lands and a groove therebetween, and the system includes a leakage port connected with an intermediate portion of the bore and with the intake side of the air blower so that oil leaking past the valve member is conducted to the blower for lubrication, and the air bleed includes recesses in the bore communicating with the air motor chamber, the air motor being operable at the second, higher predetermined air pressure to move the valve member to a position in which the groove therein connects the air bleed slots with the leakage port so that air metered by the air bleed transports leakage oil to the air blower for lubrication.

Other objects and advantages will become readily apparent from the following detailed description, taken in connection with the accompanying drawings, in which:

Figure l is a top plan view of an air-oil unit embodying my invention;

Figure 2 is a vertical sectional view taken along the line 22 of Figure l; and

Figure 3 is a schematic view of the various devices incorporated in the air-oil unit together with the passages connecting the devices.

While an illustrative embodiment of the invention is illustrated in the drawings and will be described in detail herein, the invention issusceptible of embodiment in many different forms, and it is intended that the present disclosure is to be considered as an eXemplificatio-u of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will bepointed out in the appended claims.

w atent i ce 2,832,403 Patented Apr. 29, 1958 Referring now to the drawings, the invention is illustrated in connection with an air-oil unit for use with an oil burner and may be considered as an improvement over the unit described in the copending application of Charles B. Wells, filed on November 5, 1952, as Serial Number 318,844, now Patent No. 2,766,693, granted October 16, 1956 and assigned to the assignee of this application. As in the unit there shown, the present unit may be used to supply air and metered quantities of oil to an atomizing nozzle 10. The unit comprises a casing 11 rotatably supporting a drive shaft 12 which may be driven by any suitable means. The drive shaft is connected within the unit to drive (1) an air blower 13 for providing a source of primary atomizing air under pressure for delivery to the nozzle 10, (2) a gear type lift pump 14 for delivering fuel oil from a source of supply, such as a tank, to a reservoir 15 formed in the casing 11, and (3) a piston type metering pump 16 for delivering a metered quantity of oil from the reservoir 15 to the nozzle 10 of the burner. Oil from the pump 16 is controlled by a primary air operated shutoff valve 17. The lift pump 14 may have a capacity in excess of that of the metering pump 16 and the parts are arranged to obtain a delivery of substantially air-free oil to the metering pump. Another important function of the lift pump 14 is to maintain the oil level in the reservoir above the inlet to the metering pump, and for this purpose the inlet to the lift pump is located near the top of the chamber and the inlet for the metering pump is located near the bottom of the chamber. As air bubbles will rise in the oil in the reservoir, the oil near the metering pump inlet will be free of bubbles. The excess oil delivered by the lift pump may be returned to tank (in a two line system) or (in the one line system shown) he recirculated to the pump intake through a shaft seal 18 associated with the shaft 12 and located between the air blower 13 and the gear pump 14. An annular resilient anti-hum ring 19 is mounted in the reservoir 15 by means of a battle ring 20 located between the lift pump and the metering pump, as described more fully in my copending application filed on October 25, 1955 as Serial Number 542,699.

Air is supplied to the blower 13 through an intake mufiler 21 at the right hand end of the casing 11, and air from the mufiler is delivered through a passage 22 (Figure 3) to the intake side of the blower. The blower 13 is of the vane type and comprises a circular disc-like member 23 fixed to the shaft 12 and provided with a plurality of radial slots 24 in which vanes 25 are slidable. The member 23 and the vanes 25 are surrounded by a chamber 26 which is eccentric to the axis of the shaft 12 and which is proportioned so as to provide between adjacent vanes 25, as the member 23 is rotated, an expanding chamber connected to the inlet passage 21 and a contracting chamber connected to a blower exhaust passage 27, which is in turn connected to the atomizing nozzle 10.

The lift pump 14 includes a small externally toothed gear 30 keyed to the shaft 12 and meshing with an eccentric, internally toothed ring gear 31 having a diameter larger than the gear 30 to provide space for an intervening crescent 32. A fixed outer ring 33 surrounds the ring gear 31 to enclose the gear pump within a recess forming a pumping chamber. An intake passage 34 (Figure 3) for the pump 14 opens into the upper portion of the reservoir 15. The reservoir is provided with a screen 35 and an inlet 36 from the fuel oil supply tank (not shown). The pump 14 initially draws air and creates a reduced pressure in the reservoir 15 which functions to draw oil from the storage tank into the reservoir 15 through the inlet 36 and through the screen 35. The pump 14 serves to maintain a supply of fuel oil in the reservoir a.) for delivery by the metering pump 16 to the burner nozzle 10. If the capacity of the pump 14 exceeds the capacity of the pump 16, an excess of oil will be pumped into the reservoir by the pump 14. Thus, when the level of oil in the reservoir 15 reaches the inlet passage 3 oil is drawn through the inlet 34 to the pump 14 and is discharged from the pump through an outlet passage 37 having a connection to a T-fitting 38. In single pipe installations, such as that illustrated in the drawings, fuel delivered by the lift pump to the reservoir in excess of the quantity pumped by the metering pump is directed to the shaft seal 18 through a passage 39 from the T-fitting 38. Oil is drained from the recess in which the shaft seal is mounted by means of a passage 40 connected to the bottom .of the reservoir 15. In two pipe installations, a plug 38a may be removed from the fitting 38 and a blocking plug threaded into the passage 39 to direct the excess oil through a return passage to the storage tank.

The shaft seal 18 is provided in a recess 42 in the casing 11 between the blower 13 and the lift pump 14 to prevent a leakage of fuel oil from the pump 14 along the shaft to the blower 13.

The metering pump 16 includes a cylinder block fixed to the shaft 12 for rotation therewith but slidable axially therealong by means of a splined connection including a pin 51 secured to the block and fitted in a slot formed on the shaft. The cylinder block is provided with cylinders 53 in each of which a piston 54 is reciprocable. Each piston has an end portion positioned exteriorly of the cylinder and carrying a collar 55 fixed thereto. Extending between the collars and the cylinder block and surrounding each of the end portions of the pistons are compression springs 56 which serve to constantly urge the pistons outwardly on their intake strokes.

A swash plate is provided for moving the pistons 54 on their discharge strokes to pump fuel to the atomizing nozzle, the swash plate being mounted on an end cap 58 and comprising a cam block 59 having a face 60 slanted with respect to the axis of the shaft and carrying a bearing pin 61 which rotatably supports a disc-like spin plate 62. Sliding contact is maintained between the face 60 of the cam block and the adjacent face of the spin plate to provide support for the spin plate in a direction axially of the cylinders in the block. The opposite face of the spin plate is provided with a plurality of recesses 63, each adapted to receive a rounded end portion formed on the outer end of each of the pistons. The cam block 59 which backs up the spin plate 62 is mounted for rotatable adjustment so that it may be adjusted to positions wherein the reciprocation of the pistons 54 will be placed out of phase with the pump ports to vary the volume of fluid pumped, as described more fully in my copending application filed on October 25, 1955 as Serial Number 542,685.

The intake for the metering pump includes a passage 64 formed in a port plate 65 located between the pumps 14 and 16. The passage 64 leads from the bottom of the reservoir 15 to an inlet kidney formed in the face of the port plate 65 adjacent the cylinder block 50 and communicating with the pistons on their intake stroke. Discharge from the metering pump is through an outlet kidney formed in the face of the port plate 65 and a port 66 leading from the outlet kidney to a passage 67 which connects the metering pump with the shutoff valve 17. A passage 68 leads from the shutoff valve 17 to supply fuel oil to the burner nozzle 10.

The shutoff valve 17 is constructed to control the flow of fuel to the atomizing nozzle and to be normally closed so as to prevent such flow until the primary air pressure reaches a predetermined value. Thus, the shutoff valve 17 is normally closed on the start-up of the unit and opens only after sufficient speed of the unit has been attained so as to build up primary air pressure in an amount suflicient to produce proper atomization. The valve is so constructed that should, at any time, the primary air pressure fail, the supply of fuel to the atomizing nozzle will simultaneously be cut off.

The shutoff valve 17 is located in a cylindrical bore 69 formed in the casing 11 in which a ported valve sleeve 7% is seated. A pilot valve 71, formed with separated lands 71a and 71b and a groove 71c therebetween, is slidable in the sleeve. The stem 71d of the pilot valve extends exteriorly of the sleeve 7d and into a compartment 7?. formed by the casing 11 and by a cover plate Ilia, the compartment being divided into a motor pressure chamber 73 and a spring chamber 74 by means of a diaphragm 75 which is clamped at its outer periphery to the casing 11 by the cover plate 11a. Clamping plates 76 and 7 7 are disposed on opposite sides of the central portion of the diaphragm, and the plates and the diaphragm are clamped to the valve stem by a clamping nut 78 which forces the plate 76 against a sealing ring 79 seated against the end of the land 711;. A spring 80 bears against the diaphragm plate 77 and against a spring plate 81 supported by an adjusting screw 82 on the cover plate 11a. The spring 80 functions to normally bias the valve 71 to a closed position in which the end of the valve 71 closes the passage 67 which leads from the metering pump to the valve bore and the land 71a closes a port 83 (Fig. 3) in the sleeve 70 leading to the passage 68 which connects to the nozzle 10, thus blocking communication between the metering pump and the nozzle. A port 84 formed in an intermediate portion of the valve sleeve 70 connects to a passage 85 leading to the intake side of the air blower 13, so that oil leaking past the valve land 71a is conducted through port 84 and the passage 85 to the blower 13 for lubrication thereof. In order to open the shutoff valve when suflicient air pressure is produced by the blower 13, a passageway 86 connects the motor chamber 73 with the air conduit 27 leading from the blower to the nozzle.

In systems of the type described, the air blower utilized for supplying primary air to the burner nozzle is adapted, on start up, to build up pressure sufficient for use at the atomizing nozzle, and sufficient to operate the oil shutoff valve in order. As the flow of oil to the nozzle is delayed until the necessary air flow has been established, smoky start ups of the burner are prevented. When the blower attains full speed, higher pressures of atomizing air are often developed by the blower than are necessary or desirable for delivery to the nozzle 10. Even in sys tems where the size of the blower is more nearly correlated to the delivery of the proper amounts of air to the nozzle when the blower is operating at its normal full speed, excessive air pressure may develop in the air conduit to the nozzle, as a result of the drive shaft being mementarily speeded up, for example, or, as a result of other causes. An important feature of the invention is the provision of means for controlling the air pressure at the nozzle so as to avoid a build-up of excessive pressures. This means includes an air bleed for relieving the pressure of air in the conduit to the nozzle when the pressure reaches a predetermined high value.

The air bleed comprises a plurality of slots 87 (Fig. 2) formed in the interior surface of the sleeve 70 and communicating at one end with the motor chamber 73, so that when the pressure of air in the conduit 27, the passageway 86, and the motor chamber 73 reaches a predetermined high value, the valve member 71 will be moved downward from the position shown in Fig. 2 (wherein the land 71b closes the upper ends of the slots) to a position wherein the groove 71c in the valve uncovers the upper ends of the bleed slots 87 and thereby places them in communication with the leakage port 84 so that air is metered through the passage 85 back to the intake of the blower 13.

The air bleed serves to regulate air pressure delivered to the 'atomizing nozzle so as to maintain the pressure within a suitable operating range for use at the nozzle.

The connection of the air bleed with the leakage passage '85 serves not only to relieve the air pressure in the conduit 27, but, in addition, serves to utilize the excess air in transporting leakage oil through the passage 85 to the blower 13, rather than merely exhausting the air bleed to atmosphere. These improvements are produced in a relatively simple and inexpensive manner, without the addition of complicated valve structure, by providing bleed slots which communicate with the motor chamber and with the blower intake, as described.

In operation, upon initial start up of theunit, the shutofi valve 17 will be in closed position and will remain closed until the primary air pressure becomes sufiiciently high to overcome the spring 80 which serves to maintain the valve member 71 in closed position. When the pri mary air pressure reaches a predetermined value, the diaphragm 75 will be moved downwardly against the pressure of the spring 80 to move the valve to a position in which the land 71a no longer blocks communication between the passages 67 and 68, to permit fuel pumped by the metering pump 16 to be delivered to the atomizing nozzle 10.

During the time that the unit was operated prior to the time that the primary air pressure opens the shutofi' valve, the lift pump 14 delivers oil to the reservoir 15 and thus to the intake 64 of the metering pump which in turn is operated to discharge oil from the cylinders therein. Inasmuch as the shutoff valve 17 is, during start up, in closed position and thus no outlet is provided therethrough for the fuel delivered from the cylinders of the metering pump, the pressure within the cylinders becomes sufiiciently high to move the cylinder block bodily away from the port plate against the bias of the springs 56. The cylinder block may shift axially by virtue of its splined connection 51 to the shaft 12 so that fluid delivered from within the cylinders may flow into the reservoir 15. When the shutofi? valve 17 finally opens upon the build up of the required amount of primary air pressure, the springs 56 serve to hold the end face of the cylinder block in sealing engagement against the port plate 65 so as to deliver metered quantities of oil to the atomizing nozzle.

In the event that the pressure of air in the conduit 27 exceeds a predetermined maximum value, the air pressure in the motor chamber 73 will be sufficient to move the valve member 71 to a position in which the groove 710 in the valve member places the bleed slots 87 in communication with the leakage port 84 leading from the valve bore to the intake side of the blower 13. Air is thus bled from the motor chamber 73, the passageway 86, and the conduit 27 to reduce the pressure of air in the conduit 27 to a value suitable for use at the atomizing nozzle 10.

'I claim:

1. In an air-oil device having a pump and an air blower for supplying oil and air to a burner nozzle, a control system for the oil and air supply, comprising means forming an oil passage for connecting the pump to the nozzle, an air conduit for connecting the blower to the nozzle to supply air to the nozzle, a valve mem ber controlling the oil passage, means urging the valve member to a position to block the oil passage, an air operable motor having a pressure chamber for actuating the valve member to open the oil passage, passageway means connecting the air conduit with said motor charnher to supply air to the motor chamber, and means forming an air bleed port controlled by said valve member for bleeding air from the air conduit to regulate air pressure at the nozzle, said valve member and motor being operable to open said oil passage when the air pressure reaches a first predetermined value and to open said air bleed port when the air pressure reaches a second, higher predetermined value.

2. In an air-oil device having a pump and an air blower for supplying oil and air to a burner nozzle, 21 control 75 system for the oil and air, comprising, means forming an oil passage for connecting the pump to the nozzle, an air conduit for connecting the blower to the nozzle to supply air to the nozzle, valve means located to control the fiow of oil in the oil passage including a valve bore, a valve member slidable in the bore and having an annular groove therein, means biasing the valve member to closed position blocking the oil passage, an air operable motor having a pressure chamber for actuating the valve member to open the passage, passageway means connecting the air conduit with said chamber to supply air to the chamber, the wall of said bore having an air bleed recess communicating with the motor chamber and an air bleed port connected with an intermediate portion of the bore, said motor being operable to move said valve member to open said oil passage when the air pressure in the conduit and chamber reaches a first predetermined value, and said motor being operable to move said valve member further to place said groove in communication with said air bleed recess and with said bleed port when the pressure in said conduit and chamber reaches a second, higher predetermined value in order to exhaust air from the motor pressure chamber to thereby regulate air pressure at the nozzle.

3. In an air-oil unit having a metering pump for supplying oil to a burner nozzle and an air blower for supplying air to the nozzle, a control system for the oil and air, comprising, means forming an oil passage for connecting the output side of the pump to the nozzle, an air conduit for connecting the output side of the blower to the nozzle, a. valve member located to control the flow of oil in the oil passage, a spring urging the valve member to closed position to block the oil passage, an air operated motor for actuating the valve member to open the passage, means forming a passageway connecting the air conduit and the motor, and means forming an air bleed port connected with the intake side of the blower and controlled by said valve for establishing communication between the passageway and the intake side of the blower, said valve member and motor being operable to open said oil passage when the air pressure in the conduit reaches a first predetermined value and to open said air bleed port when the air pressure in the conduit reaches a second, higher predetermined value.

4. In an air-oil system having a metering pump for supplying oil to a burner nozzle and an air blower for supplying air to the nozzle, control means for the oil and air, comprising, means forming an oil passage for connecting the output side of the pump to the nozzle, an airconduit for connecting the output side of the blower to the nozzle, valve means located to control the oil passage including a valve bore, a valve member s'lidable in the. bore and having separated lands and a groove therebetween, means biasing the valve member to closed posi tion in which one of said lands blocks the oil passage, an air operable motor having a pressure chamber for actuating the valve member to open the oil passage, passageway means connecting the air conduit with said chamber, means forming a leakage passage connected with an intermediate portion of the bore and with the intake side of the blower for conducting oil which leaks past said one land of the valve member from said oil passage to the blower for lubrication, and the wall of said bore having air bleed recesses communicating with the motor chamber, said motor being operable to move said valve member to open said oil passage when the air pressure in the conduit and chamber reaches a first predetermined value and to place said groove in the valve member in communication with said air bleed recesses and said leakage passage when the pressure in said. conduit and chamber reaches a second, higher predetermined value so that air bled from said motor chamber is returned to said blower and transports leakage oil to the blower.

5. In an air-oil system having a metering pump for 7 supplying oil to a burner nozzle and an air blower for supplying air to the nozzle, control means for the oil and air, comprising, means forming an oil passage for con-- nectiug the output side of the pump to the nozzle, an air conduit for connecting the output side of the blower to the nozzle, valve means located to control the oil passage including a valve bore, a valve member slidable in the bore and having a pair of separated lands and a groove therebetween, means forming a compartment adjacent one end of the bore, a diaphragm dividing the compartment into a spring chamber and a motor chamber, the latter chamber being disposed adjacent one end of said bore, a spring in the spring chamber for biasing the valve member to closed position in which one of said lands blocks the oil passage, said diaphragm and motor chamber forming an air operable motor for actuating the valve member to open the oil passage, passageway means connecting the air conduit with said motor chamber, means forming a leakage passage connected with an intermediate portion of the bore and with the intake side of the blower for conducting oil which leaks past said one land of the valve member from said oil passage to the blower for lubrication, and the wall of said bore having air bleed slots opening at said one end of the bore intosaid motor chamber, the other of said lands normally blocking communication between said leakage port and said bleed slots, said m'otor being operable to move said valve member to open said oil passage when the air pressure in the conduit and chamber reaches a first predetermined value and to place said groove in the valve member in communication with said air bleed slots and said leakage passage when the pressure in said conduit and motor chamber reaches a second, higher predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 

